I recently heard an adult gently pleading with a 6-year-old boy, "Come outside and go sledding. I promise you it will be better than that video game you're playing."

The boy reluctantly complied and discovered the wonderful feeling of swooshing down a snowy hill. Most people know it's better for children to not be in front of a TV or computer screen for hours on end, but why? Why is it important for kids to get out and play? What is happening from a developmental standpoint? It all has to do with developing sensory integration.

Sensory integration is the brain's natural process of interpreting and organizing the many sensory events we experience on a daily basis. Our brains constantly receive sensory information through our vision, hearing, smell, taste and touch - the five senses most people are familiar with from elementary health class.

There are two other hidden but vital senses: the "vestibular" sense and the "proprioceptive" sense.

The vestibular sense gives us information through the inner ear about movement, gravity and balance. Think of the feeling of jumping up and down, spinning or riding a roller coaster: That's your vestibular sense.

The proprioceptive sense is another internal sense that tells you where your body parts are without having to look at them. Close your eyes. Do you know where your arms, hands and feet are? Can you feel the muscles in your arms as you pick up a heavy object? Your muscles, joints, ligaments and connective tissue all have receptors that give your brain this information: That's your proprioceptive sense.

Think back to the 6-year-old boy sledding down a hill. He senses the environment through his eyes, nose, ears and skin: he feels the cold air and his winter hat and clothing on his skin; he sees the trees and snowy hill, smells the clean, cold air and hears the laughter and conversation of the other sledders. His vestibular system is activated as he goes down the hill and his proprioceptive system, in his leg and arm muscles, works hard to pull the sled back up the hill. His whole body naturally adjusts to accomplish this seemingly simple activity and he is joyfully flying down the hill again. Sensory integration makes it all possible.

Bodies and brains need a sensory rich environment, and this is especially crucial for babies and children. Sensory input is nourishment for the brain just as food is nourishment for the body. Up until the age of 7, children's brains are primarily sensory processing machines. Children experience sensation and then make motor responses; they learn what works and what doesn't and adjust their responses accordingly. This foundation of sensory-motor development is crucial for higher level learning such as reading, writing, attention and behavior as well as overall coordination and social skills. This all develops smoothly and naturally for most children, and is one of the reasons they seek activities such as running, climbing, jumping and exploring. When provided with the right opportunities, children want to move because the sensations of movement nourish their brains. And we thought it was all about having fun!

Think back to your fondest memories of childhood play. They are probably sensory-rich memories: climbing trees, roller-skating, dancing to music, jumping rope, riding bikes, building sand castles on the beach or a fort in the woods, eating s'mores by a campfire and then running through the wet grass to catch fireflies in the dark.

Now think about your children's play. Living in our computerized, technological world, children have less opportunity to use their imaginations, to touch and explore all kinds of things and to experience the feelings and challenges of all kinds of movement. Many children spend hours of "playtime" staring at a screen: TV, computer or video game. Minimal sensory systems are engaged, and for the most part the children are sedentary and solitary. Even the Wii - although a wonderful improvement on traditional video games because it encourages active movement - is still limited in providing a rich sensory experience in its "virtual" world.

So what can a parent do to make sure their child experiences "sensational" play? Limit all "screen" time to an hour or less per day. Encourage outdoor play: running, climbing, swinging, jumping, riding bikes, skating and getting messy. For indoor play provide inexpensive free-form toys that encourage children to use their imaginations, then step back and give them unstructured, child-driven playtime: building with blocks, boxes of different sizes to make things out of or to crawl in and out of, balls and targets, simple craft materials, flashlights, blankets and cushions to make indoor forts, cooking activities such as kneading bread dough or playing with Play-Doh and finger paints. Think about targeting all seven senses and the creative ideas will follow!

Unfortunately, not all children develop good sensory integration even when they're given the opportunities for sensory experiences. Neurological differences related to conditions such as autism, ADHD, some types of developmental delay or a more general sensory processing disorder can affect a child's ability to process and regulate the sensation their brain is receiving. If you notice any of the following, you might consider having your child evaluated by an occupational therapist with a background in sensory integration: